Yes.
To go to even to and from Mexico or Canada now one needs a passport or passport card for land travel.
Everyone.
When he tries to use a green card, that is a red flag.
Guy was dumb.
At the same time, if he really is a US citizen he should not have been held four months.
Four months is a long time, but he had no passport and probably never applied for a US passport. If he had, his birth records and photo ID would have been pulled up almost immediately. He probably also had no official fingerprints on file anywhere in a govt database to show a past history in the US. However, he did have a green card which would then indicate he was not a US citizen, but rather a US resident born outside the US. So he screwed himself by somehow getting an invalid green card (probably illegally) and failing to have proper identification as a US citizen. He probably didn’t even have access to his birth certificate and that had to be tracked down as well. So 4 months sounds about right.
“To go to even to and from Mexico or Canada now one needs a passport or passport card for land travel.”
When did that stupidity start?
I have always crossed those borders with just my drivers license.
Heck I even went to the Bahamas without a Passport.